Start-Process -RedirectStandardOutput issues

Question

Hi Experts,

I am trying to redirect the output and error separately to two different files when i use start-process to run PostgreSQL base backup. But std output also goes to the error file.
"-P" switch outputs the progress of PG_basebackup and i want that std ouput to go to the output file and not the error file.

Start-Process -FilePath "C:\Program Files\PostgreSQL\14\bin\pg_basebackup.exe" -ArgumentList "-D G:\FULL_Backup\Test", "-Ft", "-z", "-R", "-U pgbackup", "-w", "-P" -Wait -NoNewWindow -RedirectStandardOutput "G:\FULL_Backup\PG_Basebackup_Logs\pg_bb_test.log" -RedirectStandardError "G:\FULL_Backup\PG_Basebackup_Logs\pg_bb_err_test.log"

I simulated an error and the error goes to error file correctly

Thanks

Answer 1

Hello Udhay,

Thanks for posting your query here and we are happy to assist you regarding the PowerShell command.

The Start-Process cmdlet starts one or more processes on the local computer. By default, Start-Process creates a new process that inherits all the environment variables that are defined in the current process.

You can use following command to redirect the output / error to each file. Try placing your command to run PostgreSQL exe in input file. Following code works for me.

$processOptions = @{
FilePath = "ping.exe"
RedirectStandardInput = "C:\Users\O00\OneDrive\Desktop\PS-Scripts\TestSort.txt"
RedirectStandardOutput = "C:\Users\O00\OneDrive\Desktop\PS-Scripts\Sorted.txt"
RedirectStandardError = "C:\Users\O00\OneDrive\Desktop\PS-Scripts\SortError.txt"
UseNewEnvironment = $true
}
Start-Process @processOptions

Please find additional information in below link.

https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.management/start-process?view=powershell-7.2

Also try following option. Instead of returning the data to host, try to redirect to any file.

$pinfo = New-Object System.Diagnostics.ProcessStartInfo
$pinfo.FileName = "C:\Program Files\PostgreSQL\14\bin\pg_basebackup.exe"
$pinfo.RedirectStandardError = $true
$pinfo.RedirectStandardOutput = $true
$pinfo.UseShellExecute = $false
$pinfo.Arguments = "-D G:\FULL_Backup\Test", "-Ft", "-z", "-R", "-U pgbackup", "-w", "-P"
$p = New-Object System.Diagnostics.Process
$p.StartInfo = $pinfo
$p.Start() | Out-Null
$p.WaitForExit()
$stdout = $p.StandardOutput.ReadToEnd()
$stderr = $p.StandardError.ReadToEnd()
Write-Host "stdout: $stdout"
Write-Host "stderr: $stderr"
Write-Host "exit code: " + $p.ExitCode

Please feel to reply if you have any additional questions.

Here is a helpful page with information about Windows PowerShell

https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/powershell

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Answer 2

Not having access to the software you're using I can only ask questions.

If you placed the C:\Program Files\PostgreSQL\14\bin\pg_basebackup.exe -D G:\FULL_Backup\Test -Ft -z -R -U pgbackup -w -P into a BAT file and added the appropriate redirect of STDOUT and STDERR ( 2>G:\FULL_Backup\PG_Basebackup_Logs\pg_bb_err_test.log and 1>G:\FULL_Backup\PG_Basebackup_Logs\pg_bb_test.log ), do the streams go where you expect them to?